The insides and outsides were sitting down to dinner together as I entered the inn; and I felt, after my long walk, that it would be rather an agreeable matter to join with them. But in the hope of meeting my old friend Mr. Joss, I requested to be shown, not into the passengers' room, but into that of the coachman and guard; and with them I dined. It so chanced, however, that Mr. Joss was not out that day; and the man in the red long coat was a stranger whom I had never seen before. I inquired of him regarding Mr. Joss,—one of perhaps the most remarkable mail-guards in Europe. I have at least never heard of another who, like him, amuses his leisure on the coach-top with the "Principia" of Newton, and understands it. And the man, drawing his inference from the interest in Mr. Joss which my queries evinced, asked me whether I myself was not a coach-guard. "No," I rather thoughtlessly replied, "I am not a coach-guard." Half a minute's consideration, however, led me to doubt whether I had given the right answer. "I am not sure," I said to myself, on second thoughts, "but the man has cut pretty fairly on the point;—I daresay I am a sort of coach-guard. I have to mount my twice-a-week coach in all weathers, like any mail-guard among them all; I have to start at the appointed hour, whether the vehicle be empty or full; I have to keep a sharp eye on the opposition coaches; I am responsible, like any other mail-guard, for all the parcels carried, however little I may have had to do with the making of them up; I have always to keep my blunderbuss full charged to the muzzle,—not wishing harm to any one, but bound in duty to let drive at all and sundry who would make war upon the passengers, or attempt running the conveyance off the road; and, finally, as my friend Mr. Joss takes the "Principia" to his coach-top, I take pockets full of fossils to the top of mine, and amuse myself in fine days by working out, as I best can, the problems which they furnish. Yes, I rather think I am a coach-guard." And so, taking my seat beside my red-coated brother, who had guessed the true nature of my occupation so much more shrewdly than myself, I rode on to Elgin, where I passed the night.

It is difficult to arrange in the mind the geologic formations of Banffshire in their character as a series of deposits. The pages of the stony record which the county composes, like those of an unskilfully-folded pamphlet, have been strangely mixed together, so that page last succeeds in some places to page first, and, of the intermediate pages, some appear at the beginning of the work, and some at the end. It is not until we reach the western confines of the county, some two or three miles short of the river Spey, its terminal boundary in this direction, that we find the beds comparatively little disturbed, and arranged chronologically in their original places. In the eastern and southern parts of the shire, rocks widely separated by the date of their formation have been set down side by side in patches, occasionally of but inconsiderable extent. Now the traveller passes over a district of grauwacke, now over a re-formation of the Lias; anon he finds himself on a primary limestone,—gneiss, syenite, clay-slate, or quartz-rock; and yet anon amid the fossils of some outlier of the Old Red. The geological map of the county is, like Joseph's coat, of many colors. I remember seeing, when a boy, more years ago than I am inclined to specify, some workmen engaged in pulling down what had been a house-painter's shop, a full century before. The painter had been in the somewhat slovenly habit of cleaning his brushes by rubbing them against a hard-cast wall, which was covered, in consequence, by a many-colored layer of paint, a full half-inch in thickness, and as hard as a stone. Taking a little bit home with me, I polished it by rubbing the upper surface smooth; and, lo! a geological map. The strata of variously hued pigment, spread originally over the surface of the hard-cast wall, were cut open, by the denudation of the grindstone, into all manner of fantastic forms, and seemed thrown into all sorts of strange neighborhoods. The map lacked merely the additional perplexity of a few bold faults, with here and there a decided dike, in order to render it on a small scale a sort of miniature transcript of the geology of Banff; and I have very frequently found my thoughts reverting to it, in connection with deposits of this broken character. On a rough hard-cast basis of granite I have laid down in imagination, as if by way of priming, coat after coat of the primary rocks,—gneiss, and stratified hornblend, and mica-schist, and quartz-rock, and day-slate; and then, after breaking the coatings well up, and rubbing them well down, and so spoiling and crumpling up the work as to make their original order considerably a puzzle, I have begun anew to paint over the rough surface with thick coatings of grauwacke and grauwacke-slate. When this part of the operation was completed, I have again begun to break up and grind down,—here letting a tract of grauwacke sink into the broken primary,—there wearing it off the surface altogether,—yonder elevating the original granitic hard-cast till it rose over all the coatings, Primary and Palaeozoic. And then I have begun to paint yet a third time with thick Old Red Sandstone pigment; and yet again to break up and wear down,—here to insert a tenon of the Old Red deep into a mortise of the grauwacke, as at Gamrie,—there to dovetail it into the clay-slate, as at Tomantoul,—yonder, after laying it across the upturned quartz-rock, as at Cullen, to rub by much the greater part of it away again, leaving but mere remainder-patches and fragments, to mark where it had been. Lastly, if I had none of the superior Palaeozoic or Secondary formations to deal with, I have brushed over the whole, by way of finish, with the variously-derived coatings of the superficial deposits; and thus, as I have said, I have often completed, in idea, after the chance suggestion of the old painter's shop, my portable models of the geology of disturbed districts like the Banffshire one. The deposits of Moray are greatly less broken. Denudation has partially worn them down; but they seem to have almost wholly escaped the previous crumpling process.



CHAPTER IV.

Yellow-hued Houses Of Elgin—Geology of the Country indicated by the coloring of the Stone Houses—Fossils of Old Red north of the Grampians different from those of Old Red south—Geologic Formations at Linksfield difficult to be understood—Ganoid Scales of the Wealden—Sudden Reaction, from complex to simple, in the Scales of Fishes—Pore-covered Scales—Extraordinary amount of Design exhibited in Ancient Ganoid Scales—Holoptychius Scale illustrated by Cromwell's "fluted pot"—Patrick Duff's Geological Collection—Elgin Museum—Fishes of the Ganges—Armature of Ancient Fishes—Compensatory Defences—The Hermit-crab—Spines of the Pimelodi—Ride to Campbelton—Theories of the formation of Ardersier and Fortrose Promontories—Tradition of their construction by the Wizard, Michael Scott—A Region of Legendary Lore.

The prevailing yellow hue of the Elgin houses strikes the eye of the geologist who has travelled northwards from the Frith of Forth. He takes leave of a similar stone at Cupar-Fife,—a warmly-tinted yellow sandstone, peculiarly well-suited for giving effect to architectural ornament; and after passing along the deep-red sandstone houses of the shires of Angus and Kincardine, and the gneiss, granite, hyperstene, and mica-schist houses of Aberdeen and Banff shires, he again finds houses of a deep red on crossing the Spey, and houses of a warm yellow tint on reaching Elgin,—geologically the Cupar-Fife of the north. And the story that the colored buildings tell him is, that he has been passing, though by a somewhat circuitous route of a hundred and fifty miles, over an anticlinal geological section,—down in the scale till he reached Aberdeen and had gone a little beyond it, and then up again, until at Elgin he arrives at the same superior yellow bed of Old Red Sandstone which he had quitted at Cupar-Fife. Both beds contain the same organisms. The Holoptychius of Dura Den, near Cupar, must have sprung from the same original as the Holoptychius of the Hospital and Bishop-Mill quarries near Elgin; and it seems not improbable that the two beds, thus identical in their character and contents, may have existed, ere the upheaval of the Grampians broke their continuity, as an extended deposit, at the bottom of the same sea. But with this last and newest of the formations of the Old Red Sandstone the identity of the deposits to the south and north ceases. The strata which in the south overlie the yellow bed of the Holoptychius represent the Carboniferous period, the overlying strata in the north represent the Oolitic one. On the one side the miner sinks his shaft, and finds a true coal, composed of the Stigmaria, Calamites, Club-mosses, Ferns, and Araucarians of the Palaeozoic era; he sinks his shaft on the other side, and finds but thin seams of an imperfect lignite, composed of the Cycadeae, Pines, Sphenopteri, and Clathraria of the Secondary period. The flora which found its subsoil in the Old Red Sandstone north of the Grampians, belonged to a scene of things so much more modern than the flora which found its subsoil in the Old Red Sandstone of the south, that all its productions were green and flourishing, waving beside lake, river, and sea, at a time when the productions of the other were locked up, as now, in sand and shale, lime and clay,—the dead mummies of ages long departed.

Another thoroughly wet morning! varied only from the morning of the preceding day by the absence of wind, and the greater weight of the persevering vertical rain, that leaped upwards in myriads of little dancing pyramids from the surface of every pool. I walked out under cover of my umbrella, to renew my acquaintance with the outlier of the Weald at Linksfield, and ascertain what sort of section it now presented under the quarrying operations of the limeburners. There was, however, little to be seen; the bands of green and blue clays, alternating with strata of fossiliferous limestone, and layers of a gray shade, thickly charged with minute shells of Cypris, were sadly blurred this morning by the trail of numerous slips from above, which had fallen during the rains, and softened into mud as they rushed downwards athwart the face of the quarry: and the arched band of boulder-clay which so mysteriously underlies the deposit was, save in a few parts, wholly covered up by the debris. The occurrence of the clay here as an inferior bed, with but the cornstone of the Old Red beneath, and all the beds of the Weald resting over it, forms a riddle somewhat difficult of solution; but it is palpably not reading it aright to regard the deposit, with at least one geologist who has written on the subject, as older than the rocks above. It is, on the contrary, as a vast amount of various and unequivocal evidence demonstrates, incalculably more modern; nay, we find proof of the fact here in that very bed which has been instanced as rendering it doubtful; the clay of which the interpolation is composed is found to contain fragments, not only of the cornstone on which it rests, but also of the Wealden limestone and shales which it underlies. It forms the mere filling up of a flat-roofed cavern, or rather of two flat-roofed caverns,—for the limestone roof dipped in the centre to the cornstone floor,—which, previous to the times of the boulder-clay, had lain open in what was then, as now, an old-world deposit, charged with long extinct organisms, but which, during the iceberg period, was penetrated and occupied by the clay, as run lime penetrates and occupies the interstices of a dry-stone wall. It was no day for gathering fossils. I saw a few ganoid scales, washed by the rain from the investing rubbish, glittering on fragments of the limestone, with a few of the characteristic shells of the deposit, chiefly Unionidae; but nothing worth bringing away. The adhesive clay of the Weald, widely scattered by the workmen, and wrought into mortar by the beating rains, made it a matter of some difficulty for the struggling foot to retain the shoe, and, sticking to my soles by pounds at a time, rendered me obnoxious to the old English nickname of "rough-footed Scot." And so, after traversing the heaps, somewhat like a fly in treacle, I had to yield to the rain above and the mud beneath, and to return to do in Elgin what cannot be done equally well in almost any other town of its size in Scotland,—pursue my geological inquiries under cover.

On this, as on other occasions, I was struck by the complex and very various forms assumed by the ganoid scales of the Wealden. Throughout the Oolitic system generally, including the Lias, there obtains a singular complexity of type in these little glittering tiles of enamelled bone, which contrasts strongly with the greatly more simple style which obtained among the ganoids of the Palaeozoic period. In many of these last, as in the Coelacanth family, including the genera Holoptychius, Asterolepis, and Glyptolepis, in all their many species, with at least one genus of Dipterians, the genus Dipterus, the external outline and arrangement of scale was as simple as in any of the Cycloid family of the present time. Like slates on a roof, each single scale covered two, and was covered by two in turn; and the only point of difference which existed in relation to the laying down of these massy slates of bone, and the laying down of the very thin ones of horn which cover fish such as the carp or salmon, was, that in the massier slates, the sides, or cover,—nicely bevelled, in order to preserve an equability of thickness throughout,—were so adjusted, that two scales at their edges, where they lay the one over the other, were not thicker than one scale at its centre. Even in the other ganoids, their contemporaries, such as the Osteolepis and Diplopterus, where the scales were ranged more in the tile fashion, side by side, there was, with much ingenious carpentry in the fitting, a general simplicity of form. It would almost appear, however, that ere the ganoid order reached the times of the Weald, the simple forms had been exhausted, and that nature, abhorring repetition, and ever stamping upon the scales some specific characteristic of the creature that bore them, was obliged to have recourse to forms of a more complex and involved outline. These latter-day scales send out nail-like spikes laterally and atop, to lay hold upon their neighbors, and exhibit in their undersides grooves that accommodated the nails sent out, in turn, by their neighbors, to lay hold upon them. Their forms, too, are indescribably various and fantastic. It seems curious enough, that immediately after this extremely artificial state of things, if I may so speak, the two prevailing orders of the fish of the present day, the Cycloids and Ctenoids, should have been ushered upon the scene, and more than the original simplicity of scale restored. There took place a sudden reaction, from the fantastic and the complex to the simple and the plain.

It is further worthy of notice, that though many of the ganoid scales of the Secondary systems, including those of the Wealden, glitter as brightly in burnished enamel as the more splendent scales of the Old Red Sandstone and Coal Measures, there is a curious peculiarity exhibited in the structure of many of the older scales of the highly enamelled class, which, so far as I have yet seen, does not extend beyond the Palaeozoic period. The outer layer of the scale, which lies over a middle layer of a cellular cancellated structure, and corresponds, apparently, with that scarf-skin which in the human subject overlies the rete mucosum, is thickly set over with microscopic pores, funnel-shaped in the transverse section, and which, examined by a good glass, in the horizontal one resemble the puncturings of a sieve. The Megalichthys of the Coal Measures, with its various carboniferous congeners, with the genera Diplopterus, Dipterus, and Osteolepis of the Old Red Sandstone,—all brilliantly enamelled fish,—are thickly pore-covered. But whatever purpose these pores may have served, it seems in the Secondary period to have been otherwise accomplished, if, indeed, it continued to exist. It is a curious circumstance, that in no case do the pores seem to pass through the scale. Whatever their use, they existed merely as communications between the cells of the middle cancellated layer and the surface. In a fish of the Chalk,—Macropoma Mantelli,—the exposed fields of the scales are covered over with apparently hollow, elongated cylinders, as the little tubes in a shower-bath cover their round field of tin, save that they lie in a greatly flatter angle than the tubes; but I know not that, like the pores of the Dipterians and the Megalichthys, they communicated between the interior of the scale and its external surface. Their structure is at any rate palpably different, and they bear no such resemblance to the pores of the human skin as that which the Palaeozoic pores present.

The amount of design exhibited in the scales of some of the more ancient ganoids,—design obvious enough to be clearly read,—is very extraordinary. A single scale of Holoptychius Nobilissimus,—fast locked up in its red sandstone rock,—laid by, as it were, for ever,—will be seen, if we but set ourselves to unravel its texture, to form such an instance of nice adaptation of means to an end as might of itself be sufficient to confound the atheist. Let me attempt placing one of these scales before the reader, in its character as a flat counter of bone, of a nearly circular form, an inch and a half in diameter, and an eighth-part of an inch in thickness; and then ask him to bethink himself of the various means by which he would impart to it the greatest possible degree of strength. The human skull consists of two tables of solid bone, an inner and an outer, with a spongy cellular substance interposed between them, termed the diploe; and such is the effect of this arrangement, that the blow which would fracture a continuous wall of bone has its force broken by the spongy intermediate layer, and merely injures the outer table, leaving not unfrequently the inner one, which more especially protects the brain, wholly unharmed. Now, such also was the arrangement in the scale of the Holoptychius Nobilissimus. It consisted of its two well-marked tables of solid bone, corresponding in their dermal character, the outer to the cuticle, the inner to the true skin, and the intermediate cellular layer to the rete mucosum; but bearing an unmistakable analogy also, as a mechanical contrivance, to the two plates and the diploe of the human skull. To the strengthening principle of the two tables, however, there were two other principles added. Cromwell, when commissioning for a new helmet, his old one being, as he expresses it, "ill set," ordered his friend to send him a "fluted pot," i.e., a helmet ridged and furrowed on the surface, and suited to break, by its protuberant lines, the force of a blow, so that the vibrations of the stroke would reach the body of the metal deadened and flat. Now, the outer table of the scale of the Holoptychius was a "fluted pot." The alternate ridges and furrows which ornamented its surface served a purpose exactly similar with that of the flutes and fillets of Cromwell's helmet. The inner table was strengthened on a different but not less effective principle. The human stomach consists of three coats; and two of these, the outermost or peritoneal coat, and the middle or muscular coat, are so arranged, that the fibres of the one cross at nearly right angles those of the other. The violence which would tear the compact sides of this important organ along the fibres of the outer coat, would be checked by the transverse arrangement of the fibres of the middle coat, and vice versa. We find the cotton manufacturer weaving some of his stronger fabrics on a similar plan;—they also are made to consist of two coats; and what is technically termed the tear of the upper is so disposed that it lies at an angle of forty-five degrees with the tear of the coat which lies underneath. Now, the inner table of the scale of the Holoptychius was composed, on this principle, of various layers or coats, arranged the one over the other, so that the fibres of each lay at right angles with the fibres of the others in immediate contact with it. In the inner table of one scale I reckon nine of these alternating, variously-disposed layers; so that any application of violence, which, in the language of the lath-splitter, would run lengthwise along the grain of four of them, would be checked by the cross grain in five. In other words, the line of the tear in five of the layers was ranged at right angles with the line of the tear in four. There were thus in a single scale, in order to secure the greatest possible amount of strength,—and who can say what other purposes may have been secured besides?—three distinct principles embodied,—the principle of the two tables and diploe of the human skull,—the principle of the variously arranged coats of the human stomach,—and the principle of Oliver Cromwell's "fluted pot." There have been elaborate treatises written on those ornate flooring-tiles of the classical and middle ages, that are occasionally dug up by the antiquary amid monastic ruins, or on the sites of old Roman stations. But did any of them ever tell a story half so instructive or so strange as that told by the incalculably more ancient ganoid tiles of the Palaeozoic and Secondary periods?

I called, on my way back from Linksfield, upon my old friend Mr. Patrick Duff, and was introduced once more to his exquisite collection, with its unique ichthyolites of at least two genera of fishes of the Old Red,—the Stagonolepis and Placothorax of Agassiz,—which up to the present time are to be seen nowhere else; and various other fine specimens of rare species, which, having sat for their portraits, have their forms preserved in the great work of the naturalist of Neufchatel. He showed me, with some triumph, one of his later acquisitions,—a fine specimen of Holoptychius from the upper yellow sandstone of Bishop-Mill, which exhibits the dorsal ridge covered with a line of large overlapping scales, not at all unlike those overlapping plates which cover the tail of the lobster; for which, by the way, they were mistaken by the workman who first laid the fossil open. I examined, too, with some interest, fragments of a gigantic species of Pterichthys, belonging to an inferior division of the same Upper Old Red formation as the yellow stone, designated by Agassiz Pterichthys major, which must have attained to at least thrice the size, linearly, of even its bulkier congeners of the Lower formation of the Coccosteus. After examining many a drawer, stored, from the deposits of the neighborhood, with characteristic fossils of the Lias, the Weald, and the Oolite, and of the Upper and Lower Old Red, we set out together to expatiate amid the treasures of the Town Museum.

Among other recent additions to the Museum, there is an interesting set of the fishes of the Ganges, the donation of a gentleman long resident in India, to which Mr. Duff called my attention, as illustrative, in some of the specimens, of the more characteristic ichthyolites of the Old Red Sandstone. One numerous family, the Pimelodi, abundantly represented in the Gangetic region, in not only the rivers, but also the ponds, tanks, and estuaries of the district, is certainly worthy the careful study of the geologist. It approaches nearer, in some of its more strongly-marked genera, to the Coccosteus of the Lower Old Red, than any other tribe of existing fishes which I have yet seen. The body of the Pimelodus, from the anterior dorsal downwards, is as naked as that of the eel; whereas the head, and in several of the species the back, is armed with strong plates of naked bone, curiously fretted, as in many of the ichthyolites of the Lower, and more especially of the Upper Old Red Sandstone, into ridges of confluent tubercles, that radiate from the centre to the edges of the plates. The dorsal plate, too, when detached, as in many of the species, from the plates of the head, bears upon its inner side a strong central ridge, that deepens as it descends, till it abruptly terminates a little short of the termination of the plate, exactly as in the dorsal plate of Coccosteus, which sunk its central ridge deep into the back of the animal. The point of resemblance to be mainly noticed, however, is the contrast furnished by the powerful armature of the head and back, with the unprotected nakedness of the posterior portions of the creature;—a point specially noticeable in the Coccosteus, and apparent also, though in a lesser degree, in some of the other genera of the Old Red, such as the Pterichthyes and Asterolepides. From the snout of the Coccosteus down to the posterior termination of the dorsal plate, the creature was cased in strong armor, the plates of which remain as freshly preserved in the ancient rocks of the country as those of the Pimelodi of the Ganges on the shelves of the Elgin Museum; but from the pointed termination of the plate immediately over the dorsal fin, to the tail, comprising more than one half the entire length of the animal, all seems to have been exposed, without the protection of even a scale, and there survives in the better specimens only the internal skeleton of the fish and the ray-bones of the fins. It was armed, like a French dragoon, with a strong helmet and a short cuirass; and so we find its remains in the state in which those of some of the soldiers of Napoleon's old guard, that had been committed unstripped to the earth, may be dug up in the future on the fatal field of Borodino, or along the banks of the Dwina or the Wap. The cuirass lies still attached to the helmet, but we find only the naked skeleton attached to the cuirass. The Pterichthys to its strong helmet and cuirass added a posterior armature of comparatively feeble scales, as if, while its upper parts were shielded with plate armor, a lighter covering of ring or scale armor sufficed for the less vital parts beneath. In the Asterolepis the arrangement was somewhat similar, save that the plated cuirass was wanting: it was a strongly helmed warrior in slight scale armor; for the disproportion between the strength of the plated head-piece and that of the scaly coat was still greater than in the Pterichthys. The occipital star-covered plates are, in some of the larger specimens, fully three-quarters of an inch in thickness, whereas the thickness of the delicately-fretted scales rarely exceeds a line.

Why this disproportion between the strength of the armature in different parts of the same fish should have obtained, as in Pterichthys and Asterolepis, or why, while one portion of the animal was strongly armed, another portion should have been left, as in Coccosteus, wholly exposed, cannot of course be determined by the mere geologist. His rocks present him with but the fact of the disproportion, without accounting for it. But the natural history of existing fish, in which, as in the Pimelodi, there may be detected a similar peculiarity of armature, may perhaps throw some light on the mystery. In Hamilton's "Fishes of the Ganges" I find but little reference made to the instincts and habits of the animals described: their deep-river haunts lie, in many cases, beyond the reach of observation; and of the observations actually made, the descriptive naturalist, intent often on mere peculiarities of structure, is not unfrequently too careless. Hamilton describes the habitats of the various Indian species of Pimelodi, whether brackish estuaries, ponds, or rivers, but not their characteristic instincts. Of the Silurus, however, a genus of the same great family, I read elsewhere that some of the species, such as the Silurus glanis, being unwieldy in their motions, do not pursue their prey, which consists of small fishes, but lie concealed among the mud, and seize on the chance stragglers that come their way. And of the Pimelodus gulio, a little, strongly-helmed fish, with a naked body, I was informed by Mr. Duff, on the authority of the gentleman who had presented the specimens to the Museum, that it burrowed in the holes of muddy banks, from which it shot out its armed head, and arrested, as they passed, the minute animals on which it preyed. The animal world is full of such compensatory defences: there is a half-suit of armor given to shield half the body, and a wise instinct to protect the rest. The Pholas crispata cannot shut its valves so as to protect its anterior parts, without raising them from off those parts which lie behind: like the Irishman in the haunted house, who attempted lengthening his blanket by cutting strips from the top and sewing them on to the bottom, it loses at the one end what it gains at the other; but, hemmed round by the solid walls of the recess which it is its nature to hollow out for itself in shale or stone, the anterior parts, though uncovered by the shell, are not exposed. By closing its valves anteriorly, it shuts the door of its little house, made like that of the coney-folk of Scripture, in the rock; and then, of the entire cell in which it dwells so secure, what is not shut door is impregnable wall. The remark of Paley, that the "human animal is the only one which is naked, and the only one which can clothe itself," is by no means quite correct. One half the hermit crab is as naked as the "human animal," and even less fitted for exposure; for it consists of a thin-skinned, soft, unmuscular bag, filled with delicate viscera; but not even the human animal is more skilful in clothing himself in the spoils of other animals than the hermit crab in wrapping up its naked bag in the strong shell of some dead fusus or buccinum, which it carries about with it in all its peregrinations, as at once clothes, armor, and house. Nature arms its front, and it is itself wise enough to arm its rear. Now, it seems not improbable that the half-armed Coccosteus, a heavy fish, indifferently furnished with fins, may have burrowed, like the recent Silurus glanis or Pimelodus gulio, in a thick mud,—of the existence of which in vast quantity, during the times of the Old Red Sandstone, the dark Caithness flagstones, the fetid breccia of Strathpeffer, and the gray stratified clays of Cromarty, Moray, and Banff, unequivocally testify; and that it may have thus not only succeeded in capturing many of its light-winged contemporaries, which it would have vainly pursued in open sea, but may have been enabled also to present to its enemies, when assailed in turn, only its armed portions, and to protect its unarmed parts in its burrow. It is further worthy of notice, that many of the Pimelodi are furnished with spines, not, like those ichthyodorulites which occur so frequently in the older Secondary and Palaeozoic divisions, unfinished in appearance at their lower extremity, as if, like the spines of the ancient Acanthodi, or those of the recent dog-fish (Spinax acanthias), they had been simply embedded in the flesh, but bearing, like the wings of the Pterichthys, an articulated aspect. Those of the Pimelodus rita and Pimelodus gagata are of singular beauty; and when the creatures have no further use for them, and the mud of the Ganges has been consolidated into shale or baked into flagstone around them, they will make very exquisite fossils. A correct drawing of the plates and spines of some of the members of the Pimelodi family, with a portion of the internal skeletons, arranged in their proper places, but divested of those more destructible parts to which they are attached, would serve admirably to show what strange forms fish not greatly removed from the ordinary type may assume in the fossil state, and might throw some light on the extraordinary appearance assumed, as ichthyolites, by the old family of the Cephalaspians.

The geological department of the Elgin Museum is not yet very complete. The private collections of the locality, by forestalling, greatly restrict the supply from the rich deposits in the neighborhood, and have an unquestioned right to do so. The Museum contains, however, several interesting organisms. I saw, among the others, a specimen of Diplopterus, that showed the form and position of the fins of this rather rare ichthyolite much better than any of the Morayshire specimens portrayed by Agassiz in his great work; and beside it, one of the two specimens of Pterichthys oblongus which he figures, and on which he establishes the species. The other individual,—a Cromarty specimen,—graces my little collection. The gloomy day passed pleasantly in deciphering, with so accomplished a geologist as Mr. Duff, these curious hieroglyphics of the old world, that tell such wonderful stories, and in comparing viva voce, as we were wont to do long years before in lengthy epistles, our respective notions regarding the true key for laying open their more occult meanings. And, after sharing with him in his family dinner, I again took my seat on the mail, as a chill, raw evening was falling, and rode on, some six or eight and twenty miles, to Campbelton. The rain pattered drearily through the night on my bed-room window; and as frequent exposure to the wet had begun to tell on a constitution not altogether so strong as it had once been, I awakened oftener than was quite comfortable, to hear it. The morning, however, was dry, though gray and sunless; and, taking an early breakfast at the inn, I traversed the flat gravelly points of Ardersier and Fortrose, that, projecting like moles far into the Frith, narrow the intervening ferry to considerably less than one-third the width which it would present were they away. The origin of these long detrital promontories, which form, when viewed from the heights on either side, so peculiar a feature in the landscape, and which, were they directly opposite, instead of being set down a mile awry, would shut up the opening altogether, has not yet been satisfactorily accounted for. One special theory assigns their formation to the agency of the descending tide, striking in zig-gig style, in consequence of some peculiarity of the coast-line or of the bottom, from side to side of the Frith, and depositing a long trail of sand and gravel, at nearly right angles with the beach, first on the one shore and then on the other. But why the tide, which runs in various zig-zag crossings in the course of the Frith, should have the effect here, and nowhere else, of raising two vast mounds, each a full mile and a quarter in length, with an average breadth of from two to five furlongs, is by no means very apparent. Certainly the present tides of the Frith could not have formed them, nor could they have been elevated to their present average height of ten or twelve feet over the flood-line in a sea standing at the existing level. If they in reality originated in this cause, it must have been ere the latter upheavals of the land or recessions of the sea, when the great Caledonian Valley existed as a narrow ocean sound, swept by powerful currents. Upon another and entirely different hypothesis, these flat promontories have been regarded as the remains, levelled by the waves, and gapped direct in the middle by the tide, of a vast transverse morain of the great valley, belonging to the same glacial age as the lateral morains some ten or fifteen miles higher up, that extend from the immediate neighborhood of Inverness to the mansion-house of Dochfour. But this hypothesis, like the other, is not without its difficulties. Why, for instance, should the promontories be a mile awry? There is, however, yet another mode of accounting for their formation, which I am not in the least disposed to criticise.

They were constructed, says tradition, through the agency of the arch-wizard Michael Scott. Michael had called up the hosts of Faery to erect the cathedral of Elgin and the chanonry kirk of Fortrose, which they completed from foundation to ridge, each in a single night,—committing, in their hurry, merely the slight mistake of locating the building intended for Elgin in Fortrose, and that intended for Fortrose in Elgin; but, their work over and done, and when the magician had no further use for them, they absolutely refused to be laid; and, like a posse of Irish laborers thrown out of a job, came thronging round him, clamoring for more employment. Fearing lest he should be torn in pieces,—a catastrophe which has not unfrequently happened in such circumstances in the olden time, and of which those recent philanthropists who engage themselves in finding work for the unemployed may have perhaps entertained some little dread in our own days,—he got rid of them for the time by setting them off in a body to run a mound across the Moray Frith from Fortrose to Ardersier. Toiling hard in the evening of a moonlight night, they had proceeded greatly more than two-thirds towards the completion of the undertaking, when a luckless Highlander passing by bade God-speed the work, and, by thus breaking the charm, arrested at once and forever the construction of the mound, and saved the navigation of Inverness.

I stood for a few seconds at the Burn of Rosemarkie undecided whether I should take the Scarfs-Craig road,—a break-neck path which runs eastwards along the cliffs, and which, though the rougher, is the more direct Cromarty line of the two,—or the considerably better though longer line of the White Bog, which strikes upwards along the burn in a westerly direction, and joins the Cromarty and Inverness highway on the moor of the Maolbuie. I had got into a part of the country where every little locality, and every more striking feature in the landscape, has its associated tradition; and the pause of a few moments at the two roads recalled to my memory the details of a ghost-story, long regarded in the district in which it was best known as one of the most authentic of its class, but which seems by no means inexplicable on natural principles.[13]



CHAPTER V.

Rosemarkie and its Scaurs—Kaes' Craig—A Jackdaw Settlement—"Rosemarkie Kaes" and "Cromarty Cooties"—"The Danes," a Group of Excavations—At Home in Cromarty—The Boulder-clay of Cromarty "begins to tell its story"—One of its marked Scenic Peculiarities—Hints to Landscape Painters—"Samuel's Well"—A Chain of Bogs geologically accounted for—Another Scenic Peculiarity—"Ha-has of Nature's digging"—The Author's earliest Field of Hard Labor—Picturesque Cliff of Boulder-clay—Scratchings on the Sandstone—Invariable Characteristic of true Boulder-clay—Scratchings on Pebbles in the line of the longer axis—Illustration from the Boulder-clay of Banff.

Rosemarkie, with its long narrow valley and its red abrupt scaurs,[14] is chiefly interesting to the geologist for its vast beds of the boulder-clay. I am acquainted with no other locality in the kingdom where this deposit is hollowed into ravines so profound, or presents precipices so imposing and lofty. The clay lies thickly over most part of the Black Isle and the peninsula of Easter Ross,—both soft sandstone districts,—bearing everywhere an obvious relation, as a deposit, to both the form and the conditions of exposure of the existing land,—just as the accumulated snow of a long-lying snow-storm, exposed to the drifting wind, bears relation to the heights and hollows of the tracts which it covers. On the higher eminences the clay forms a comparatively thin stratum, and in not a few instances it has been wholly worn away; while on the lower grounds, immediately over the old coast line, and in the sides of hollow valleys,—exactly such places as we might expect to see the snow occupying most deeply after a night of drift,—we find it accumulated in vast beds of from eighty to an hundred feet in thickness. One of these occurs in the opening of the narrow valley along which my course this morning lay, and is known far and wide,—for it forms a marked feature in the landscape, and harbors in its recesses a countless multitude of jackdaws,—as the "Kaes' Craig of Rosemarkie." It presents the appearance of a hill that had been cut sheer through the middle from top to base, and exhibits in its abrupt front a broad red perpendicular section of at least a hundred feet in height, barred transversely by thin layers of sand, and scored vertically by the slow action of the rains. Originally it must have stretched its vanished limb across the opening like some huge snow-wreath accumulated athwart a frozen rivulet; but the incessant sweep of the stream that runs through the valley has long since amputated and carried it away; and so only half the hill now remains. The Kaes' Craig resembles in form a lofty chalk cliff, square, massy, abrupt, with no sloping fillet of vegetation bound across its brow, but precipitous direct from the hill-top. The little ancient village of Rosemarkie stretches away from its base on the opposite side of the stream; and on its summit and along its sides, groups of chattering jackdaws, each one of them as reflective and philosophic as the individual immortalized by Cowper, look down high over the chimneys into the streets. The clay presents here, more than in almost any other locality with which I am acquainted, the character of a stratified deposit; and the numerous bands of sand by which the cliff is horizontally streaked from top to bottom we find hollowed, as we approach, into a multitude of circular openings, like shot-holes in an old tower, which form breeding-places for the daw and the sand-martin. The biped inhabitants of the cliff are greatly more numerous than the biped inhabitants of the quiet little hamlet below; and on Fortrose fair-days, when, in virtue of an old feud, the Rosemarkie boys were wont to engage in formidable bickers with the boys of Cromarty, I remember, as one of the invading belligerents, that, in bandying names with them in the fray, we delighted to bestow upon them, as their hereditary sobriquet, given, of course, in allusion to their feathered neighbors, the designation of the "Rosemarkie kaes." Cromarty, however, is two-thirds surrounded by the waters of a frith abounding in sea-fowl; and the little fellows of Rosemarkie, indignant at being classed with their kaes, used to designate us with hearty emphasis, in turn, as the "Cromarty cooties," i.e., coots.

A little higher up the valley, on the western side, there occurs in the clay what may be termed a group of excavations, composing a piece of scenery ruinously broken and dreary, and that bears a specific character of its own which scarce any other deposit could have exhibited. The excavations are of considerable depth and extent,—hollows out of which the materials of pyramids might have been taken. The precipitous sides are fretted by jutting ridges and receding inflections, that present in abundance their diversified alternations of light and shadow. The steep descents form cycloid curves, that flatten at their bases, and over which the ferruginous stratum of mould atop projects like a cornice. Between neighboring excavations there stand up dividing walls, tall and thin as those of our city buildings, and in some cases broken at their upper edges into rows of sharp pinnacles or inaccessible turf-coped turrets; while at the bottom of the hollows, washed by the runnels which, in the slow lapse of years, have been the architects of the whole, we find cairn-like accumulations of water-rolled stones,—the disengaged pebbles and boulders of the deposit. The boulders and pebbles project also from the steep sides, at all heights and of all sizes, like the primary masses inclosed in our ancient conglomerates, when exhibited in wave-worn precipices,—forcing upon the mind the conclusion that the boulder-clay is itself but an unconsolidated conglomerate of the later periods, which occupies nearly the same relative position to the existing vegetable mould, with all its recent productions, that the great conglomerate of the Old Red Sandstone occupies in relation to the lower ichthyolite beds of that system, with their numerous extinct organisms. But its buried stones are fretted with hieroglyphic inscriptions, in the form of strange scratchings and polishings, grooves, ridges, and furrows,—always associated with the boulder-clays,—which those of the more ancient conglomerates want, and which, though difficult to read, seem at length to be yielding up the story which they record. Of this, however, more anon. Viewed by moonlight, when the pale red of the clay where the beam falls direct is relieved by the intense shadows, these excavations of the valley of Rosemarkie form scenes of strange and ghostly wildness: the projecting, buttress-like angles,—the broken walls,—the curved inflections,—the pointed pinnacles,—the turrets, with their masses of projecting coping,—the utter lack of vegetation, save where the heath and the furze rustle far above,—all combine to form assemblages of dreary ruins, amid which, in the solitude of night, one almost expects to see spirits walk. These excavations have been designated, from time immemorial, by the neighboring town's-people, as "the Danes;" but whether the name be, as is most probable, merely a corruption of an appropriate enough Saxon word, "the dens," or derived, as a vague tradition is said to testify, from the ages of Danish invasion, it is not quite the part of the geologist to determine. It may be worth mentioning, however, from its bearing on the point, that there are two excavations in the boulder-clay near Cromarty, one of which has been long known by the name of "the Morial's Den," while the other, greatly smaller in size, rejoices in the double diminutive of "the Little Dennie." For an hour or so the Danes proved agreeable though somewhat silent companions; and then, climbing the opposite side of the valley, I gained the high road, and, walking on to Cromarty, found myself once more among "the old familiar faces."

In a few days the storm blew by; and as the prolonged rains had cleared out the deep ravines of the district, and given to the boulder-clay in which they are scooped a freshness in its section analogous to fresh fracture in rocks of harder consistency, I availed myself of the facilities afforded me in consequence, for exploring it once more. It has long constituted one of the hardest of the many riddles with which our Scottish deposits exercise the patience and ingenuity of the geologist. I remember a time when, after passing a day under its barren scaurs, or hid in its precipitous ravines, I used to feel in the evening as if I had been travelling under the cloud of night, and had seen nothing. It was a morose and taciturn companion, and had no speculation in it. I might stand in front of its curved precipices, red, yellow or gray, according to the prevailing average color of the rocks on which it rests, and mark their water-rolled boulders, of all qualities and sizes, sticking out in bold relief from the surface, like the rock-like protuberances that roughen the rustic basements of the architect, from the line of the wall; but I had no open sesame to form vistas through them into the recesses of the past. I saw merely the stiff pastry matrix of which they are composed, and the inclosed pebbles. But the boulder-clay has of late become more sociable; and, though with much hesitancy and irresolution, like old Mr. Spectator on the first formal opening of his mouth,—a consequence, doubtless, in both cases of previous habits of silence long indulged,—it begins to tell its story. And a most curious story it is.

The morning was clear, but just a little chill; and a soft covering of snow, that had fallen during the storm on the flat summit of Ben-Wevis, and showed its extreme tenuity by the paleness of its tint of watery blue, was still distinctly visible at the distance of full twenty miles. The sun, low in the sky,—for the hour was early,—cast its slant rays athwart the prospect, giving to each nearer bank and hillock, and to the more distant protuberances on the mountain-sides, those well-defined accompaniments of shadow that serve by throwing the minor features of a landscape upon the eye in bold relief, to impart to it an air of higher finish and more careful filling up than it ever bears under a more vertical light. I took the road which, leading westward from the town towards Invergordon Ferry, skirts the Frith on the one hand, and runs immediately under the noble escarpment of green bank formed by the old coast line on the other. Fully two-thirds of the entire height of the rampart here, which rises in all about a hundred feet over the sea-level, is formed of the boulder-clay; and I am acquainted with no locality in which the deposit presents more strongly, for at least the first half mile, one of its marked scenic peculiarities. It is furrowed vertically on the slope, as if by enormous flutings in the more antique Doric style; and the ridges by which these are separated,—each from a hundred to a hundred and fifty feet in length, and from five-and-twenty to thirty feet in average height,—resemble those burial mounds with which the sexton frets the churchyard turf; with this difference, however, that they seem the burial mounds of giants, tall and bulky as those that of old warred against the gods. They are striking enough to have caught the eye of the children of the place, and are known among them as the Giants' Graves. I could fain have taken their portrait in a calotype this morning, as they lay against the green bank,—their feet to the shore, and their heads on the top of the escarpment,—like patients on a reclining bed, and strongly marked, each by its broad bar of yellow light and of dark shadow, like the ebon and ivory buttresses of the poet. This little vignette, I would have said to the landscape painter, represents the boulder-clay, after its precipitous banks—worn down, by the frosts and rains of centuries, into parallel runnels, that gradually widened into these hollow grooves—had sunk into the angle of inclination at which the disintegrating agents ceased to operate, and the green sward covered all up. You must be studying these peculiarities of aspect more than ever you studied them before. There is a time coming when the connoisseur will as rigidly demand the specific character of the various geologic rocks and deposits in your hills, scaurs, and precipices, as he now demands specific character in your shrubs and trees.

It is worthy the notice of the young geologist, who has just set himself to study the various effects produced on the surface of a country by the deposits which lie under it, that for about a quarter of a mile or so, the base of the escarpment here is bordered by a line of bogs, that bear in the driest weather their mantling of green. They are fed with a perennial supply of water, by a range of deep-seated springs, that come bursting out from under the boulder-clay; and one of their number, which bears I know not why, the name of Samuel's Well, and yields its equable flow at an equable temperature, summer and winter, into a stone trough by the way-side, is not a little prized by the town's-people, and the seamen that cast anchor in the opposite roadstead, for the lightness and purity of its water. What is specially worthy of notice in the case is, the very definite beginning and ending of the chain of bogs. All is dry at the base of the escarpment, up to the point at which they commence; and then all is equally dry at the point at which they terminate. And of exactly the same extent,—beginning where the bogs begin, and ending where they end,—we may trace an ancient stratum of pure sand,—of considerable thickness, intercalated between the base of the clay and the superior surface of the Old Red Sandstone. It is through this permeable sand that the profoundly seated springs find their way to the surface,—for the clay is impermeable; and where it comes in contact with the rock on either side of the arenaceous stratum, the bogs cease. The chain of green bogs is a consequence of the stratum of permeable sand. I have in vain sought this ancient layer of sand,—decidedly of the same era with the argillaceous bed which overlies it,—for aught organic. A single shell, so unequivocally of the period of the boulder-clay as to occur at the base of the deposit, would be worth, I have said, whole drawerfuls of fossils furnished by the better-known deposits. But I have since seen in abundance shells of the boulder-clay.

There is another scenic peculiarity of the clay, which the neighborhood of Cromarty finely illustrates, and of which my walk this morning furnished numerous striking instances. The Giants' Graves—to borrow from the children of the place—occur on the steep slopes of the old coast line, or in the sides of ravines, where the clay, as I have said, had once presented a precipitous front, but had been gradually moulded, under the attritive influences of the elements, into series of alternating ridges and furrows, which, when they had flattened into the proper angle, the green sward covered up from further waste. But the deep dells and narrow ravines in which many ranges of these graves occur are themselves peculiarities of the deposit. Wherever the boulder-clay lies thick and continuous, as in the parish of Cromarty, on a sloping table-land, every minute streamlet cuts its way to the solid rock at the bottom, and runs through a deep dell, either softened into beauty by the disintegrating process, or with all its precipices standing up raw and abrupt over the stream. Four of these ravines, known as the "Old Chapel Burn," the "Ladies' Walk," the "Morial's Den," and the "Red Burn," each of them cutting the escarpment of the ancient coast line from top to base, and winding far into the interior, occur in little more than a mile's space; and they lie still more thickly farther to the west. These dells of the boulder clay, in their lower windings,—for they become shallower and tamer as they ascend, till they terminate in the uplands in mere drains, such as a ditcher might excavate at the rate of a shilling or two per yard,—are eminently picturesque. On those gentler slopes where the vegetable mould has had time and space to accumulate, we find not a few of the finest and tallest trees of the district. There is a bosky luxuriance in their more sheltered hollows, well known to the schoolboy what time the fern begins to pale its fronds, for their store of hips, sloes, and brambles; and red over the foliage we may see, ever and anon as we wend upwards, the abrupt frontage of some precipitous scaur, suited to remind the geologist, from its square form and flat breadth of surface, of the cliffs of the chalk. When viewed from the sea, at the distance of a few miles, these ravines seem to divide the sloping tracts in which they occur into large irregular fields, laid out considerably more in accordance with the principles of the landscape gardener than the stiffly squared rectilinear fields of the agriculturist. They are ha-has of Nature's digging; and their bottom and sides in this part of the country we still find occupied in a few cases—though in many more they have been ravaged by the wasteful axe—by noble forest-hedges, tall enough to overtop, in at least their middle reaches, the tracts of table-land which they divide.

I passed, a little farther on, the quarry of Old Red Sandstone, with a huge bank of boulder-clay resting over it, in which I first experienced the evils of hard labor, and first set myself to lessen their weight by becoming an observer of geological phenomena. It had been deserted apparently for many years; and the debris of the clay partially covered up, in a sloping talus, the frontage of rock beneath. Old Red Sandstone and boulder-clay, a broad bar of each!—such was the compound problem which the excavation propounded to me when I first plied the tool in it,—a problem equally dark at the time in both its parts. I have since got on a very little way with the Old Red portion of the task; but alas for the boulder-clay portion of it! A bar of impenetrable shadow has rested long and obstinately over the newer deposit; and I scarce know whether the light which is at length beginning to play on its pebbly front be that of the sun or of a delusive meteor. But courage, patient hearts! the boulder-clay will one day yield up its secret too. Still further on by a few hundred yards, I could have again found use for the calotype, in transferring to paper the likeness of a protuberant picturesque cliff, which, like the Giants' Graves, could have belonged, of all our Scotch deposits, to only the boulder-clay. It stands out, on the steep acclivity of a furze-covered bank, abrupt as a precipice of solid rock, and yet seamed by the rain into numerous divergent channels, with pyramidal peaks between; and, combining the perpendicularity of a true cliff with the water-scooped furrows of a yielding clay, it presents a peculiarity of aspect which strikes, by its grotesqueness, eyes little accustomed to detect the picturesque in landscape. I remember standing to gaze upon it when a mere child; and the fisher children of the neighboring town still tell that "it has been prophesied" it will one day fall, "and kill a man and a horse on the road below,"—a legend which shows it must have attracted their notice too.

I selected as the special scene of exploration this morning, a deep ravine of the boulder-clay, which had been recently deepened still more by the waters of a mill-pond, that had burst during a thunder-shower, and, after scooping out for themselves a bed in the clay some twelve or fifteen feet deep, where there had been formerly merely a shallow drain, had then tumbled into the ravine, and bared it to the rock. The sandstones of the district, soft and not very durable, show the scratched and polished surfaces but indifferently well, and, when exposed to the weather, soon lose them; but in the bottom of the runnel by which the ravine is swept I found them exceedingly well marked,—the polish as decided as the soft red stone could receive, and the lines of scratching running in their general bearing due east and west, at nearly right angles with the course of the stream. Wherever the rock had been laid bare during the last few months, there were the markings; wherever it had been laid bare for a few twelvemonths, they were gone. I next marked a circumstance which has now for several years been attracting my attention, and which I have found an invariable characteristic of the true boulder-clay. Not only do the rocks on which the deposit rests bear the scratched and polished surfaces, but in every instance the fragments of stone which it incloses bear the scratchings also, if from their character capable of receiving and retaining such markings, and neither of too coarse a grain nor of too hard a quality. If of limestone, or of a coherent shale, or of a close, finely-grained sandstone, or of a yielding trap, they are scratched and polished,—invariably on one, most commonly on both their sides; and it is a noticeable circumstance, that the lines of the scratchings occur, in at least nine cases out of every ten, in the lines of their longer axes. When decidedly oblong or spindle-shaped, the scratchings run lengthwise, preserving in most cases, on the under and upper sides, when both surfaces are scratched, a parallelism singularly exact; whereas, when of a broader form, so that the length and breadth nearly approximate,—though the lines generally find out the longer axis, and run in that direction,—they are less exact in their parallelism, and are occasionally traversed by cross furrows. Of such certain occurrence is this longitudinal lining on the softer and finer-grained pebbles of the boulder-clay, that I have come to regard it as that special characteristic of the deposit on which I can most surely rely for purposes of identification. I am never quite certain of the boulder-clay when I do not detect it, nor doubtful of the true character of the deposit when I do. When examining, for instance, the accumulation of broken Liasic materials in the neighborhood of Banff, I made it my first care to ascertain whether the bank inclosed fragments of stone or shale bearing the longitudinal markings; and felt satisfied, on finding that it did, that I had discovered the period of its re-formation.



CHAPTER VI.

Organisms of the Boulder-clay not unequivocal—First Impressions of the Boulder-clay—Difficulty of accounting for its barrenness of Remains—Sir Charles Lyell's reasoning—A Fact to the contrary—Human Skull dug from a Clay-bank—The Author's Change of Belief respecting Organic Remains of the Boulder-clay—Shells from the Clay at Wick—Questions respecting them settled—Conclusions confirmed by Mr. Dick's Discoveries at Thurso—Sir John Sinclair's Discovery of Boulder-clay Shells in 1802—Comminution of the Shells illustrated—Cyprina islandica—Its Preservation in larger Proportions than those of other Shells accounted for—Boulder-clays of Scotland reformed during the existing Geological Epoch—Scotland in the Period of the Boulder-clay "merely three detached groups of Islands"—Evidence of the Subsidence of the Land in Scotland—Confirmed by Rev. Mr. Cumming's conclusion—High-lying Granite Boulders—Marks of a succeeding elevatory Period—Scandinavia now rising—Autobiography of a Boulder desirable—A Story of the Supernatural.

For the greater part of a quarter of a century I had been finding organisms in abundance in the boulder-clay, but never anything organic that unequivocally belonged to its own period. I had ascertained that it contains in Ross and Cromarty nodules of the Old Red Sandstone, which bear inside, like so many stone coffins, their well laid out skeletons of the dead; but then the markings on their surface told me that when the boulder-clay was in the course of deposition, they had been exactly the same kind of nodules that they are now. In Moray, it incloses, I had found, organisms of the Lias; but they also testify that they present an appearance in no degree more ancient at the present time than they did when first enveloped by the clay. In East and West Lothian too, and in the neighborhood of Edinburgh, I had detected in it occasional organisms of the Mountain Limestone and the Coal Measures; but these, not less surely than its Liasic fossils in Moray, and its Old Red ichthyolites in Cromarty and Ross, belonged to an incalculably more ancient state of things than itself; and—like those shrivelled manuscripts of Pompeii or Herculaneum, which, whatever else they may record, cannot be expected to tell aught of the catastrophe that buried them up—they throw no light whatever on the deposit in which they occur. I at length came to regard the boulder-clay—for it is difficult to keep the mind in a purely blank state on any subject on which one thinks a good deal—as representative of a chaotic period of death and darkness, introductory, mayhap, to the existing scene of things.

After, however, I had begun to mark the invariable connection of the clay, as a deposit, with the dressed surfaces on which it rests, and the longitudinal linings of the pebbles and boulders which it incloses, and to associate it, in consequence, with an ice-charged sea and the Great Gulf Stream, it seemed to me extremely difficult to assign a reason why it should be thus barren of remains. Sir Charles Lyell states, in his "Elements," that the "stranding of ice-islands in the bays of Iceland since 1835 has driven away the fish for several successive seasons, and thereby caused a famine among the inhabitants of the country;" and he argues from the fact, "that a sea habitually infested with melting ice, which would chill and freshen the water, might render the same uninhabitable by marine mollusca." But then, on the other hand, it is equally a fact that half a million of seals have been killed in a single season on the meadow-ice a little to the north of Newfoundland, and that many millions of cod, besides other fish, are captured yearly on the shores of that island, though grooved and furrowed by ice-floes almost every spring. Of the seal family it is specially recorded by naturalists, that many of the species "are from choice inhabitants of the margins of the frozen seas towards both poles; and, of course, in localities in which many such animals live, some must occasionally die." And though the grinding process would certainly have disjointed, and might probably have worn down and partially mutilated, the bones of the amphibious carnivora of the boulder period, it seems not in the least probable, judging from the fragments of loose-grained sandstone and soft shale which it has spared, that it would have wholly destroyed them. So it happened, however, that from North Berwick to the Ord Hill of Caithness, I had never found in the boulder-clay the slightest trace of an organism that could be held to belong to itself; and as it seems natural to build on negative evidence, if very extensive, considerably more than mere negative evidence, whatever the circumstances, will carry, I became somewhat skeptical regarding the very existence of boulder-fossils,—a skepticism which the worse than doubtful character of several supposed discoveries in the deposit served considerably to strengthen. The clay forms, when cut by a water-course, or assailed on the coast by some unusually high tide, a perpendicular precipice, which in the course of years slopes into a talus; and as it exhibits in most instances no marks of stratification, the clay of the talus—a mere re-formation of fragments detached by the frosts and rains from the exposed frontage—can rarely be distinguished from that of the original deposit. Now, in these consolidated slopes it is not unusual to find remains, animal and vegetable, of no very remote antiquity. I have seen a human skull dug out of the reclining base of a clay-bank once a precipice, fully six feet from under the surface. It might have been deemed the skull of some long-lived contemporary of Enoch,—one of the accursed race, mayhap,

"Who sinned and died before the avenging flood."

But, alas! the laborer dug a little further, and struck his pickaxe against an old rybat that lay deeper still. There could be no mistaking the character of the champfered edge, that still bore the marks of the tool, nor that of the square perforation for the lock-bolt; and a rising theory, that would have referred the boulder-clay to a period in which the polar ice, set loose by the waters of the Noachian deluge, came floating southwards over the foundered land, straightway stumbled against it, and fell. Both rybat and skull had come from an ancient burying-ground, that occupies a projecting angle of the table-land above. I must now state, however, that my skepticism has thoroughly given way; and that, slowly yielding to the force of positive evidence, I have become as assured a believer in the comminuted recent shells of the boulder-clay as in the belemnites of the Oolite and Lias, or the ganoid ichthyolites of the Old Red Sandstone.

I had marked, when at Wick, on several occasions, a thick boulder-clay deposit occupying the southern side of the harbor, and forming an elevated platform, on which the higher parts of Pulteneytown are built; but I had noted little else regarding it than that it bears the average dark-gray color of the flagstones of the district, and that some of the granitic boulders which protrude from its top and sides are of vast size. On my last visit, however, rather more than two years ago, when sauntering along its base, after a very wet morning, awaiting the Orkney steamer, I was surprised to find, where a small slip had taken place during the rain, that it was mottled over with minute fragments of shells. These I examined, and found, so far as, in their extremely broken condition, I dared determine the point, that they belonged in such large proportion to one species,—the Cyprina islandica of Dr. Fleming,—that I could detect among them only a single fragment of any other shell,—the pillar, apparently, of a large specimen of Purpura lapillus. Both shells belong to that class of old existences,—long descended, without the pride of ancient descent,—which link on the extinct to the recent scenes of being. Cyprina islandica and Purpura lapillus not only exist as living molluscs in the British seas, but they occur also as crag-shells, side by side with the dead races that have no place in the present fauna. At this time, however, I could but think of them simply in their character as recent molluscs; and as it seemed quite startling enough to find them in a deposit which I had once deemed representative of a period of death, and still continued to regard as obstinately unfossiliferous, I next set myself to determine whether it really was the boulder-clay in which they occurred. Almost the first pebble which I disengaged from the mass, however, settled the point, by furnishing the evidence on which for several years past I have been accustomed to settle it;—it bore in the line of its longer axis, on a polished surface, the freshly-marked grooves and scratchings of the iceberg era. Still, however, I had my doubts, not regarding the deposit, but the shells. Might they not belong merely to the talus of this bank of boulder-clay?—a re-formation, in all probability, not more ancient than the elevation of the most recent of the old coast lines,—perhaps greatly less so. Meeting with an intelligent citizen of Wick, Mr. John Cleghorn, I requested him to keep a vigilant eye on the shells, and to ascertain for me, when opportunity offered, whether they occurred deep in the deposit, or were restricted to merely the base of its exposed front. On my return from Orkney, he kindly brought me a small collection of fragments, exclusively, so far as I could judge, of Cyprina islandica, picked up in fresh sections of the clay; at the same time expressing his belief that they really belonged to the deposit as such, and were not accidental introductions into it from the adjacent shore. And at this point for nearly two years the matter rested, when my attention was again called to it by finding, in the publication of Mr. Keith Johnston's admirable Geological Map of the British Islands, edited by Professor Edward Forbes, that other eyes than mine had detected shells in the boulder-clay of Caithness. "Cliffs of Pleistocene," says the Professor, in one of his notes attached to the map, "occur at Wick, containing boreal shells, especially Astarte borealis."

I had seen the boulder-clay characteristically developed in the neighborhood of Thurso; but, during a rather hurried visit, had lacked time to examine it. The omission mattered the less, however, as my friend Mr. Robert Dick is resident in the locality; and there are few men who examine more carefully or more perseveringly than he, or who can enjoy with higher relish the sweets of scientific research. I wrote him regarding Professor Forbes's decision on the boulder-clay of Wick and its shells; urging him to ascertain whether the boulder-clay of Thurso had not its shells also. And almost by return of post I received from him, in reply, a little packet of comminuted shells, dug out of a deposit of the boulder-clay, laid open by the river Thorsa, a full mile from the sea, and from eighty to a hundred feet over its level. He had detected minute fragments of shell in the clay about a twelvemonth before; but a skepticism somewhat similar to my own, added to the dread of being deceived by mere surface shells, recently derived from the shore in the character of shell-sand, or of the edible species carried inland for food, and then transferred from the ash-pit to the fields, had not only prevented him from following up the discovery, but even from thinking of it as such. But he eagerly followed it up now, by visiting every bank of the boulder-clay in his locality within twenty miles of Thurso, and found them all charged, from top to bottom, with comminuted shells, however great their distance from the sea, or their elevation over it. The fragments lie thick along the course of the Thorsa, where the encroaching stream is scooping out the clay for the first time since its deposition, and laying bare the scratched and furrowed pebbles. They occur, too, in the depths of solitary ravines far amid the moors, and underlie heath, and moss, and vegetable mould, on the exposed hill-sides. The farm-house of Dalemore, twelve miles from Thurso as the crow flies, and rather more than thirteen miles from Wick, occupies, as nearly as may be, the centre of the county; and yet there, as on the sea-shore, the boulder-clay is charged with its fragments of marine shells. Though so barren elsewhere on the east coast of Scotland, the clay is everywhere in Caithness a shell-bearing deposit; and no sooner had Mr. Dick determined the fact for himself, at the expense of many a fatiguing journey, and many an hour's hard digging, than he found that it had been ascertained long before, though, from the very inadequate style in which it had been recorded, science had in scarce any degree benefited by the discovery. In 1802 the late Sir John Sinclair, distinguished for his enlightened zeal in developing the agricultural resources of the country, and for originating its statistics, employed a mineralogical surveyor to explore the underground treasures of the district; and the surveyor's journal he had printed under the title of "Minutes and Observations drawn up in the course of a Mineralogical Survey of the County of Caithness, ann. 1802, by John Busby, Edinburgh." Now, in this journal there are frequent references made to the occurrence of marine shells in the blue clay. Mr. Dick has copied for me the two following entries,—for the work itself I have never seen:—"1802, Sept. 7th.—Surveyed down the river [Thorsa] to Geize; found blue clay-marl, intermixed with marine shells in great abundance." "Sept. 12th.—Set off this morning for Dalemore. Bored for shell-marl in the 'grass-park;' found it in one of the quagmires, but to no great extent. Bored for shell-marl in the 'house-park.' Surveyed by the side of the river, and found blue clay-marl in great plenty, intermixed with marine shells, such as those found at Geize. This place is supposed to be about twenty miles from the sea; and is one instance, among many in Caithness, of the ocean's covering the inland country at some former period of time."

The state of keeping in which the boulder-shells of Caithness occur is exactly what, on the iceberg theory, might be premised. The ponderous ice-rafts that went grating over the deep-sea bottom, grinding down its rocks into clay, and deeply furrowing its pebbles, must have borne heavily on its comparatively fragile shells. If rocks and pebbles did not escape, the shells must have fared but hardly. And very hardly they have fared: the rather unpleasant casualty of being crushed to death must have been a greatly more common one in those days than in even the present age of railways and machinery. The reader, by passing half a bushel of the common shells of our shores through a barley-mill, as a preliminary operation in the process, and by next subjecting the broken fragments thus obtained to the attritive influence of the waves on some storm-beaten beach for a twelvemonth or two, as a finishing operation, may produce, when he pleases, exactly such a water-worn shelly debris as mottles the blue boulder-clays of Caithness. The proportion borne by the fragments of one species of shell to that of all the others is very extraordinary. The Cyprina islandica is still by no means a rare mollusc on our Scottish shores, and may, on an exposed coast, after a storm, be picked up by dozens, attached to the roots of the deep-sea tangle. It is greatly less abundant, however, than such shells as Purpura lapillus, Mytilus edule, Cardium edule, Littorina littorea, and several others; whereas in the boulder-clay it is, in the proportion of at least ten to one, more abundant than all the others put together. The great strength of the shell, however, may have in part led to this result; as I find that its stronger and massier portions,—those of the umbo and hinge-joint,—are exceedingly numerous in proportion to its slimmer and weaker fragments. "The Cyprina islandica," says Dr. Fleming, in his "British Animals," "is the largest British bivalve shell, measuring sometimes thirteen inches in circumference, and, exclusively of the animal, weighing upwards of nine ounces." Now, in a collection of fragments of Cyprina sent me by Mr. Dick, disinterred from the boulder-clay in various localities in the neighborhood of Thurso, and weighing in all about four ounces, I have detected the broken remains of no fewer than sixteen hinge joints. And on the same principle through which the stronger fragments of Cyprina were preserved in so much larger proportion than the weaker ones, may Cyprina itself have been preserved in much larger proportion than its more fragile neighbors. Occasionally, however,—escaped, as if by accident,—characteristic fragments are found of shells by no means very strong,—such as Mytilus, Tellina, and Astarte. Among the univalves I can distinguish Dentalium entale, Purpura lapillus, Turritella terebra, and Littorina littorea, all existing shells, but all common also to at least the later deposits of the Crag. And among the bivalves Mr. Dick enumerates,—besides the prevailing Cyprina islandica,—Venus casina, Cardium edule, Cardium echinatum, Mytilus edule, Astarte danmoniensis (sulcata), and Astarte compressa, with a Mactra, Artemis, and Tellina.[15] All the determined species here, with the exception of Mytilus edule, have, with many others, been found by the Rev. Mr. Cumming in the boulder-clays of the Isle of Man; and all of them are living shells at the present day on our Scottish coasts. It seems scarce possible to fix the age of a deposit so broken in its organisms, on the principle that would first seek to determine its per centage of extinct shells as the data on which to found. One has to search sedulously and long ere a fragment turns up sufficiently entire for the purpose of specific identification, even when it belongs to a well-known living shell; and did the clay contain some six or eight per cent. of the extinct in a similarly broken condition (and there is no evidence that it contains a single per cent. of extinct shells), I know not how, in the circumstances, the fact could ever be determined. A lifetime might be devoted to the task of fixing their real proportion, and yet be devoted to it in vain. All that at present can be said is, that, judging from what appears, the boulder-clays of Caithness, and with them the boulder-clays of Scotland generally, and of the Isle of Man,—for they are all palpably connected with the same iceberg phenomena, and occur along the same zone in reference to the sea-level,—were formed during the existing geological epoch.

These details may appear tediously minute; but let the reader mark how very much they involve. The occurrence of recent shells largely diffused throughout the boulder-clays of Caithness, at all heights and distances from the sea at which the clay itself occurs, and not only connected with the iceberg phenomena by the closest juxtaposition, but also testifying distinctly to its agency by the extremely comminuted state in which we find them, tell us, not only according to old John Busby, "that the ocean covered the inland country at some former period of time," but that it covered it to a great height at a time geologically recent, when our seas were inhabited by exactly the same mollusca as inhabit them now, and so far as yet appears, by none others. I have not yet detected the boulder-clay at more than from six to eight hundred feet over the level of the sea; but the travelled boulders I have often found at more than a thousand feet over it; and Dr. John Fleming, the correctness of whose observations few men acquainted with the character of his researches or of his mind will be disposed to challenge, has informed me that he has detected the dressed and polished surfaces at least four hundred feet higher. There occurs a greenstone boulder, of from twelve to fourteen tons weight, says Mr. M'Laren, in his "Geology of Fife and the Lothians," on the south side of Black Hill (one of the Pentland range), at about fourteen hundred feet over the sea. Now fourteen or fifteen hundred feet, taken as the extreme height of the dressings, though they are said to occur greatly higher, would serve to submerge in the iceberg ocean almost the whole agricultural region of Scotland. The common hazel (Corylus avellana) ceases to grow in the latitude of the Grampians, at from one thousand two hundred to one thousand five hundred feet over the sea level; the common bracken (Pteris aquilina) at about the same height; and corn is never successfully cultivated at a greater altitude. Where the hazel and bracken cease to grow, it is in vain to attempt growing corn.[16] In the period of the boulder-clay, then, when the existing shells of our coasts lived in those inland sounds and friths of the country that now exist as broad plains or fertile valleys, the sub-aerial superficies of Scotland was restricted to what are now its barren and mossy regions, and formed, instead of one continuous land, merely three detached groups of islands,—the small Cheviot and Hartfell group,—the greatly larger Grampian and Ben Nevis group,—and a group intermediate in size, extending from Mealfourvonny, on the northern shores of Loch Ness, to the Maiden Paps of Caithness.